In aircraft industry several methods exist today for providing narrow pieces of prepreg tapes. A prepreg tape is a form of composite material, wherein the resin is mixed with high-strength fibers and is partially cured. The narrow longitudinal pieces or so called fillets are, during assembly, filled in cavities formed in structural elements, junction plies, etc. (e.g. under panels applied onto a supporting structure of an aircraft's aileron, rudder, fuselage, wing etc.) for preventing deformation and/or weakening of the area near the cavity. Also plastic material fillets made of thermoplast or thermosetting resins exist made without any reinforcement elements therein.
The manufactory of fillets is today expensive and complicated. For example, U.S. Pat. No. 4,559,005 discloses a method of forming fillets by means of a machine with forming rolls rotated by a drive mechanism, the rolls having die grooves defining an orifice which shape corresponds to the cross-sectional shape of the fillet. Variable sized grooves of the rolls provide various sized fillets. The prepreg tape is fed into the machine through guide holes of the latter. The machine solves the problem related to time consuming and that little compaction is achieved by hand preparation of fillets.
Furthermore, U.S. Pat. No. 6,562,436 discloses a laminated fillet. Carbon fiber is oriented in different directions for providing increased structural properties. The profile of the fillet is cut out from the prepreg tape by means of an ultrasonic knife.
The object of the present invention is to overcome the drawbacks of known technique and to provide a solution alternative to hand preparation of fillets, which solution is non-expensive, simple, time saving and provides an user-friendly flexible module system.